[clang] [compiler-rt] [llvm] [InstrFDO][TypeProf] Implement binary instrumentation and profile read/write (PR #66825)
Snehasish Kumar via cfe-commits
cfe-commits at lists.llvm.org
Wed Mar 6 13:09:09 PST 2024
================
@@ -1237,6 +1259,101 @@ void InstrLowerer::maybeSetComdat(GlobalVariable *GV, Function *Fn,
GV->setLinkage(GlobalValue::InternalLinkage);
}
+static inline bool shouldRecordVTableAddr(GlobalVariable *GV) {
+ if (!profDataReferencedByCode(*GV->getParent()))
+ return false;
+
+ if (!GV->hasLinkOnceLinkage() && !GV->hasLocalLinkage() &&
+ !GV->hasAvailableExternallyLinkage())
+ return true;
+
+ // This avoids the profile data from referencing internal symbols in
+ // COMDAT.
+ if (GV->hasLocalLinkage() && GV->hasComdat())
+ return false;
+
+ return true;
+}
+
+// FIXME: Introduce an internal alias like what's done for functions to reduce
+// the number of relocation entries.
+static inline Constant *getVTableAddrForProfData(GlobalVariable *GV) {
+ auto *Int8PtrTy = PointerType::getUnqual(GV->getContext());
+
+ // Store a nullptr in __profvt_ if a real address shouldn't be used.
+ if (!shouldRecordVTableAddr(GV))
+ return ConstantPointerNull::get(Int8PtrTy);
+
+ return ConstantExpr::getBitCast(GV, Int8PtrTy);
+}
+
+void InstrLowerer::getOrCreateVTableProfData(GlobalVariable *GV) {
+ assert(!DebugInfoCorrelate &&
+ "Value profiling is not supported with lightweight instrumentation");
+ if (GV->isDeclaration() || GV->hasAvailableExternallyLinkage())
+ return;
+
+ if (GV->getName().starts_with("llvm.") ||
+ GV->getName().starts_with("__llvm") ||
+ GV->getName().starts_with("__prof"))
+ return;
+
+ // VTableProfData already created
+ auto It = VTableDataMap.find(GV);
+ if (It != VTableDataMap.end() && It->second)
----------------
snehasish wrote:
Ok, sounds reasonable to me.
https://github.com/llvm/llvm-project/pull/66825
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